Rumours or fact?

I've still had no satisfactory explanation as to how to make my 12-24 focus - even on infinity (which isn't that far away on that) in anything other than bright sunshine.

Improved AF is waaaay up on my priority list for a new camera - and I don't shoot birds/airplanes/etc that people usually have problems with, yet spend more time fighting AF than anything else.

Then something is clearly wrong. I was using the 12-24mm in all lighting conditions from darkest cellars to bright sunshine last week at Beamish, and there were no problems at all.

Back to be checked and repaired I think. If other lenses are OK, then your 12-24mm has the problem.

An afterthought - you are using centre-point only focus? If not, then I suggest you do. Focus on your main subject, half press on shutter release to lock, recompose, fire shutter. Works every time.

It was in Don's response to my earlier comment about workarounds:
I took from that that he was talking about shooting video.

Well of course there isn't. I know that very well

All I'm suggesting is that better would be better, and to blindly accept the necessity to use MF as perfectly Ok, is to communicate to the manufacturer that improvements in that area are unimportant.

I had a play with a Nikon D100 a couple of years ago, with a very ordinary consumer zoom on the front. It was much, much better at getting a quick, positive focus lock in a fairly dark room, than my K10D was, also just with a kit lens on it.

This isn't the rigorous scientific comparison that I'd normally insist on, admittedly, but I was left with the feeling that the Pentax AF struggled a lot more than the Nikon - and a fairly old Nikon at that.

But you don't shoot moving objects much in low light, do you John?

I find the AF fine too for stationary things in low light.

Admittedly, shooting moving dancers in dark clubs as I sometimes do, is a much tougher ask, and of course, I've become reasonably good at the other techniques, but having to use them makes life a lot harder than I'd like.

'Brilliant' is definitely not a word I'd use about Pentax AF in the harder situations. 'Occasionally Ok', 'Generally frustrating' a lot more so.

John, c'mon, I'm not that much of a newbie ...

As a matter of fact, I do use the centre point in all circumstances (often with the half-press and reframe technique), except for aircraft in flight.

The Auto AF point selection is then much more effective, since it will continue to find the aircraft even if you fail to track it exactly on the centre point.

No insult intended, but when looking for solutions I never assume any more than I already know. We can all learn things, including myself, and we can all have blank spots sometimes.

Using AF for aircraft in that way makes me wonder about the shutter delay though. Ideally we would release the shutter just before the ideal moment, to allow for maybe 100ms delay before the shutter actually fires.

With AF, the focus has locked and maybe 100ms later (plus our own reaction time) when the shutter releases, the plane is no longer in the same position.

I will try this as soon as the opportunity arises and see how it compares with the MF I would normally use for such situations. Until then, from my persepctive I am only musing on the possibilities.

I can't see how a particular lens can affect the AF abilites of a camera - I come back to my theory that Pentax never expect people to put one on a Kx...

anyway, I posted this random shot a while back to illustrate - should be easy-peasy, its Infinity. Not even particularly dark (just overcast). But instead, hunt-hunt-hunt-won't-lock-oh-I-give-up-MANUALSWITCH!




(yes, I know, I forgot the CPL that day...)

Oh well, I'm just going out now, will be back shortly with another lens that they probably didn't expect see on a Kx... really must buy a licence for Lightroom though!

I know, John, hence my ''

None taken, it just made me laugh.

Absolutely. Blank spots - I can truly claim some expertise there


Indeed. My experience is that sharp results are considerably easier when they're flying past, rather than towards or away.

For example, this is dreadful, whereas this isn't.

I got lucky with this, which is better, but there were a lot more duds.

Feel free to stop by sometime soon and see if it's the same on my K10D.

I see that many seem to have some problems in low light auto and manual focus. Use this; always focus with the longest range of your zoom lens then zoom out to the zoom setting that you want to use. Ie. 18 -85 lend focus at 85 zoom out to 18.....same for any lens. Works well.

Yes, but the thing is, people shooting every other brand say the same. I am all for improved AF (who wouldn't be?) but the truth is I prefer MF and the control it gives. There is no way I expect a camera to know more than I do or to be faster than I am. Maybe someday it will get to that point, but it's more fun this way, so I'm not losing sleep over it.

(I have done paid gigs of children dancing, with six or more kids on stage at a time and only two or three minutes to get a great shot of each one. Quick movements in poor light. So I do know what it is like!)

That would work well if zooms were true zooms, but most these days are not. They are varifocal lenses, not parfocal zooms.

What this means is that they need refocusing at every focal length selected. You will only get away with this if it's a very small aperture and DOF covers the error created as you zoom.

I've always found the 12-24 to be very good at AF (on a K2D). So perhaps your KX theory is right, Flossie. Though it sounds rather strange - surely JR's hunch that there's a fault with the lens is much more likely?

Thanks ChrisA for the offer - but I need to spend some time first trying to find out if its just Operator Error - see if I can get a reproducable scenario that it won't focus properly in first, because it only seems to happen when I'm not expecting it!